For example, a vehicle provided with an apparatus capable of executing various information processing such as route guidance on the basis of geographic data becomes widely used. The vehicle provided with such an information processing apparatus may send and receive various information such as traffic information, geographic information, route information, image information, and music information to and from various types of information sending and receiving apparatus such as an information delivering center or other vehicle provided with such an information processing apparatus with wireless communications. In the case of sending and receiving data (information) to and from the information delivering center or other vehicle, it is common to carry out data communications by a client server system, by which data (information) is centrally controlled using an in-vehicle telephone or a cellular phone (mobile phone) connected to the apparatus. In addition, a method of carrying out data communications between vehicles with a wireless LAN (local area network) has already been proposed (see Japanese Laid-Open Patent Application No. 2001-136190).
However, there is a problem that the communication costs are expensive in the case of data communication system using in-vehicle phones or cellular phones because such a system to account based on the amount of packets while sending and receiving data (information) is normally utilized. Further, the communication speed of such a phone that has already been put to practical use is low speed (for example, currently, the maximum speed thereof is 384 kbps (kilo bit/second), and an area where the apparatuses can communicate with each other is limited to an available area of such a phone. Moreover, the developing and operating costs for a server in a client server system are required.
On the other hand, in the case of the method using a wireless LAN, there is an advantage (merit) that no costs for development of a server and no communication costs are required. However, since data transmission (data sending and receiving) between particular vehicles is assumed, only information (data) to be sent and received is sent and received when the data transmission between the vehicles is carried out separately, and therefore information that an arbitrary vehicle possesses (that is, information stored in information storage means such as memory of an arbitrary vehicle) cannot be obtained.
Further, most data communications between vehicles are carried out while the vehicles are moving independently, and therefore a time when each of two vehicle carrying out data transmission resides in a data transferable area may be short in the case where the data transmission is carried out while the vehicles are moving. For this reason, the event that the data transmission cannot be terminated completely may occur quite frequently. In that case, since data that has already received is incomplete, it is required that the corresponding data is obtained again from another vehicle or the like. Further, if the data transmission cannot be terminated completely even in this case, such a data transmitting operation may be repeated, and it is thus inefficient.